The present invention relates to contactless integrated circuits and portable electronic devices produced by means of these integrated circuits.
In recent years, so-called xe2x80x9ccontactlessxe2x80x9d integrated circuits have been developed and devised, that are capable of receiving or transmitting data by inductive coupling, through an antenna coil. Examples of embodiments of these integrated circuits are described in applications WO 98/02840, WO 98/02980, WO 98/05123, WO 98/06057 and WO 98/06056 in the name of the applicant. Furthermore, these integrated circuits are being standardized and are more particularly the subject of the draft standard ISO 14443, mentioned herein without restriction.
FIG. 1 is a very schematic representation of a contactless integrated circuit 1 connected to an antenna coil 2. The integrated circuit 1 is active when coil 2 is dipped into a magnetic field FLD sent by a data send/receive station 5 which itself comprises, for that purpose, an antenna coil 6. The magnetic field FLD sent by the station 5 oscillates at a determined frequency, such as 13.56 MHz for example, according to ISO 14443 standard. Generally speaking, data transmission DTr from the station 5 to the integrated circuit 1 is carried out by modulating the amplitude of the antenna signal, with a 100% (ISO 14443/A) or 10% (ISO 14443/B) depth of modulation for example. Data transmission DTx from the integrated circuit 1 to the station 5 is carried out by modulating the coil 2 load. The load modulation signal is passed on by inductive coupling in the coil 6 of the station 2 wherein it is filtered and decoded to retrieve the data DTx that it contains.
These integrated circuits are found in numerous applications and enable more particularly contactless smart cards, contactless electronic badges, contactless electronic labels, etc. to be produced.
One idea, which represents in itself one aspect of the present invention, is to produce a portable electronic device comprising a combination of contactless integrated circuits.
Indeed, the present invention is based on the consideration according to which a combination of several contactless integrated circuits is capable of offering various advantages and to be used in various applications, as demonstrated below.
However, in order to be advantageous, a device comprising several contactless integrated circuits must be compact and offer a maximum distance of communication with each of the integrated circuits which is not too short. xe2x80x9cMaximum distance of communicationxe2x80x9d shall mean the distance of communication above which no data transmission is possible, due to too low inductive coupling.
Yet, a simple juxtaposition of contactless integrated circuits each equipped with an antenna coil does not enable a satisfactory compromise to be found between minimum overall dimensions of the device and a satisfactory maximum distance of communication, pursuant to the principle according to which the maximum distance of communication increases in proportion to the size of the antenna coil. Thus, the juxtaposition of several small micromodules incorporating a contactless integrated circuit and an antenna small in size leads to produce a device the size of which is satisfactory, but wherein each micromodule offers a short maximum distance of communication. Conversely, the juxtaposition of several modules each incorporating a contactless integrated circuit and an antenna of large diameter leads to produce a device offering a satisfactory maximum distance of communication but having considerable overall dimensions and a significant cost price due to the cost of manufacturing each antenna and of the raw material used.
Thus, the present invention aims to provide a device comprising a combination of contactless integrated circuits which have reduced overall dimensions while offering a satisfactory maximum distance of communication.
This object is achieved by providing a device comprising a combination of at least two contactless integrated circuits, each integrated circuit being connected to an individual antenna coil to send and/or receive data by inductive coupling, the device comprising a collective antenna coil that is larger in size than the individual antenna coils of the integrated circuits, and means for arranging the individual coil of an integrated circuit proximate to the collective coil, at least when data are to be read and/or written in the integrated circuit, so that the individual coil of the integrated circuit is inductively coupled to the collective coil, the integrated circuits being arranged or programmed to implement an anti-collision protocol which enables a data send and/or receive station to select one, and only one, integrated circuit during communication with the device.
According to one embodiment, the individual coil of each integrated circuit is permanently coupled to the collective coil.
According to one embodiment, the collective coil, the integrated circuits and the individual antenna coils are arranged on a common support, the integrated circuits and the individual antenna coils being placed in the centre of the collective coil.
According to one embodiment, the collective coil is arranged on a first support, the integrated circuits are arranged on one or more supports which are different from the first support, the device comprising means for moving the support of an integrated circuit closer to the support of the collective coil at least when data are to be read and/or written in the integrated circuit.
According to one embodiment, the collective coil and the integrated circuits are arranged on substantially flat supports structured around an axis so as to form a sort of notebook.
According to one embodiment, the flat supports are jackets.
According to one embodiment, each integrated circuit and its individual antenna coil are produced in the form of a small micromodule.
According to one embodiment, the integrated circuits are arranged or programmed to form together an equivalent integrated circuit the total data storage capacity of which is greater than the individual storage capacity of each integrated circuit.
According to one embodiment, each integrated circuit comprises a datum in its memory representing the rank of the integrated circuit with regard to the other integrated circuits of the device, with a view to adding the data storage capacities of the integrated circuits by adding storage areas.